The present invention relates to jet engine thrust reversers and, more particularly, to a thrust reverser actuation system with the ability to determine the position of system components from the rotational position of a motor within the system.
When a jet-powered aircraft lands, the landing gear brakes and imposed aerodynamic drag loads (e.g., flaps, spoilers, etc.) of the aircraft may not be sufficient to slow the aircraft down in the required amount of runway distance. Thus, jet engines on most aircraft include thrust reversers to enhance the braking of the aircraft. When deployed a thrust reverser redirects the rearward thrust of the jet engine to a forward or semi-forward direction to decelerate the aircraft upon landing. When in the stowed position, the thrust reverser is in a position that generally does not redirect the engine thrust.
Various thrust reverser designs are commonly known, and the particular design utilized depends, at least in part, on the engine manufacturer, the engine configuration, and the propulsion technology being used. Thrust reverser designs used most prominently with turbofan jet engines fall into three general categories: (1) cascade-type thrust reversers; (2) target-type thrust reversers; and (3) pivot door thrust reversers. Each of these designs employs a different type of moveable thrust reverser component to change the direction of the jet thrust.
Cascade-type thrust reversers are normally used on high-bypass ratio jet engines. This type of thrust reverser is located on the circumference of the engine""s midsection and, when deployed, exposes and redirects air flow through a plurality of cascade vanes positioned on the outside of the engine. The moveable thrust reverser component in the cascade may includes several translating sleeves or cowls (xe2x80x9ctranscowlsxe2x80x9d) that are deployed to expose the cascade vanes. Target-type reversers, also referred to as clamshell reversers, are typically used with low-bypass ratio jet engines. Target-type thrust reversers use two doors as the moveable thrust reverser component to block the entire jet thrust coming from the rear of the engine. These doors are mounted on the aft portion of the engine and form the rear part of the engine nacelle. Pivot door thrust reversers may utilize four doors on the engine nacelle as the moveable thrust reverser components. In the deployed position, these doors extend outwardly from the nacelle to redirect the jet thrust.
The primary use of thrust reversers is, as noted above, to enhance the braking power of the aircraft, thereby shortening the stopping distance during landing. Hence, thrust reversers are usually deployed during the landing process to slow the aircraft. The moveable thrust reverser components in each of the above-described designs are moved between the stowed and deployed position by means of actuators. Power to drive the actuators may come from one or more drive motors or from a hydraulic or pneumatic fluid system connected to the actuators, depending on the system design requirements.
One way of monitoring and determining the position of a thrust reverser is to use one or more position sensors mounted on a gearhead reducer. However, the degree of accuracy attained by such sensors may not be sufficiently precise for some applications. In particular, the degree of inaccuracy of these position sensors may be great enough that a position sensor could indicate that the thrust reverser is stowed when it is not.
When highly accurate thrust reverser position information is desired, employing higher accuracy position sensors may add both excess weight and cost to the thrust reverser system. Additionally, under some system architectures, position sensors provide the sole source of position information for the thrust reverser components. Thus, a secondary source of position information is lacking to backup the primary indicator. However, it should be appreciated that current thrust reverser systems are generally reliable and safe.
In view of the foregoing, there is a need for a thrust reverser system that accurately determines the position of the system""s moveable components to solve one or more of the drawbacks identified above, including the accurate determination of the absolute position of a thrust reverser component, and/or the avoidance of the weight and cost associated with current position sensors, and/or that has a back-up determination of thrust reverser component position without adding additional components and/or weight to the existing system. The present invention satisfies one or more of these needs.
The present invention provides an improved thrust reverser system and method that determines thrust reverser position based on the rotational position of the motor used to drive the thrust reverser actuators.
In one embodiment of the present invention, and by way of example only, a system for determining the position of a jet engine thrust reverser component includes a motor, at least one actuator, a first rotational position sensor, and a circuit. The actuator is coupled to the motor and is operable to move the thrust reverser component in response to rotation of the motor. The first rotational position sensor is operable to sense a rotational position of the motor and supply a first rotational position signal representative thereof. The circuit is coupled to receive at least the first rotational position signal and is operable to determine thrust reverser component position based at least in part on the first rotational position signal.
In another exemplary embodiment, a jet engine thrust reverser control system includes an electric motor, at least one actuator, a first rotational position sensor, and a circuit. The actuator is coupled to the electric motor and is operable to move a thrust reverser in response to rotation of the motor. The first rotational position sensor is operable to sense a rotational position of the electric motor and supply a first rotational position signal representative thereof. The circuit is coupled to receive at least the first rotational position signal and is operable to determine thrust reverser position based at least in part on the first rotational position signal.
In yet another exemplary embodiment, in a thrust reverser control system having a motor operably coupled to move a thrust reverser component between a stowed position and a deployed position, a method of determining jet engine thrust reverser component position includes rotating the motor, counting revolutions of the motor, and converting the counted motor revolutions into thrust reverser component position.
In still a further exemplary embodiment, in a thrust reverser control system having a motor operably coupled to move a thrust reverser component between a stowed position and a deployed position, and that implements an algorithm to determine thrust reverser component position from a position of the motor, a method of declaring the algorithm valid includes rotating the motor to move the thrust reverser component toward the stowed position, determining that the thrust reverser component is stowed, and declaring the algorithm valid when thrust reverser component stowage is determined.
Other independent features and advantages of the preferred system and method will become apparent from the following detailed description, taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the invention.